我用过两次，

1.一次是数据库以前数据可以为null，现在不想为null，然后不想改代码，所以在插入或修改数据的时候，查一次，把为null的数据变一下，字符串变“”，数字变0或-1

下面的就是设置监听

方法EntityInterceptor.java

package com.banksteel.erp.pfpurchase.util;

import java.lang.reflect.InvocationTargetException;

import java.lang.reflect.Method;

import java.util.*;

import org.apache.ibatis.executor.Executor;

import org.apache.ibatis.mapping.MappedStatement;

import org.apache.ibatis.mapping.SqlCommandType;

import org.apache.ibatis.plugin.Interceptor;

import org.apache.ibatis.plugin.Intercepts;

import org.apache.ibatis.plugin.Invocation;

import org.apache.ibatis.plugin.Plugin;

import org.apache.ibatis.plugin.Signature;

/**

*

* @description: 防止插入出现null

* @projectName：finance-inventorybook-service

* @author：

* @createTime：2017年11月30日 上午9:37:30

*/

@Intercepts(value =

{ @Signature(type = Executor.class, method = "update", args =

{ MappedStatement.class, Object.class }) })

public class EntityInterceptor implements Interceptor

{

@Override

public Object intercept(Invocation invocation) throws Throwable

{

final Object[] args = invocation.getArgs();

MappedStatement ms = (MappedStatement) args[0];

Object obj = args[1];

// 插入时初始化为null的字段

if (SqlCommandType.INSERT == ms.getSqlCommandType())

{

if (obj instanceof List>)

{

List> list = (List>) obj;

for (Object item : list)

{

null2default(item);

}

} else

{

null2default(obj);

}

}

return invocation.proceed();

}

@Override

public Object plugin(Object target)

{

return Plugin.wrap(target, this);

}

@Override

public void setProperties(Properties properties)

{

}

/**

*

* @description: 将实体类的属性由null设置为默认值，这里没有变数字的，只变了字符串

* @param obj

* @author：

* @createTime：2017年11月2日 下午5:19:56

*/

public static void null2default(T obj)

{

if (null == obj)

{

return;

}

Method[] methods=obj.getClass().getMethods();

Map setMethodMap = new HashMap<>();

for (Method method : methods){

if(method.getName().startsWith("set")){

setMethodMap.put(method.getName(),method);

}

}

for (Method method : methods){

if((method.getName().length() < 3) || (!method.getName().startsWith("get"))){

//只调用get函数

continue;

}

//排除带有参数列表的方法

Class>[] pts =method.getParameterTypes();

if(null != pts && 0 < pts.length){

continue;

}

//排除值不为null的get方法

try {

if(null != method.invoke(obj)){

continue;

}

} catch (IllegalAccessException e) {

e.printStackTrace();

} catch (InvocationTargetException e) {

e.printStackTrace();

}

//找出get方法对应的set方法

char[] cs = method.getName().toCharArray();

cs[0] = 's';

Method setMethod = setMethodMap.get(String.valueOf(cs));

if(null == setMethod){

continue;

}

//设置默认值

Class> retClazz = method.getReturnType();

try {

if(Objects.equals(retClazz,String.class)){

setMethod.invoke(obj, "");

}

} catch (IllegalAccessException e) {

e.printStackTrace();

} catch (InvocationTargetException e) {

e.printStackTrace();

}

}

setMethodMap.clear();

}

// public static void main(String args[]){

// ResourceAuditInfo ra = new ResourceAuditInfo();

// null2default(ra);

// System.out.println(JSONObject.toJSONString(ra));

// }

}

2.如果不是用上面的分页，就用另一种监听

class="com.banksteel.openerp.commons.interceptor.RebuildSqlInterceptor" />

Rexxx.java,这里可以查找到要修改的sql或查询的条件，再这里都可以修改

package com.banksteel.openerp.commons.interceptor;

import java.sql.Connection;

import java.util.List;

import java.util.Properties;

import org.apache.ibatis.executor.statement.StatementHandler;

import org.apache.ibatis.mapping.BoundSql;

import org.apache.ibatis.mapping.MappedStatement;

import org.apache.ibatis.mapping.ParameterMapping;

import org.apache.ibatis.plugin.Interceptor;

import org.apache.ibatis.plugin.Intercepts;

import org.apache.ibatis.plugin.Invocation;

import org.apache.ibatis.plugin.Plugin;

import org.apache.ibatis.plugin.Signature;

import org.apache.ibatis.reflection.MetaObject;

import org.apache.ibatis.reflection.SystemMetaObject;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

import com.banksteel.openerp.commons.filter.SaasParameter;

import com.banksteel.openerp.commons.utils.RebuildSqlUtils;

import cn.mysteel.util.StringUtils;

/**

* 重建SQL语句拦截器

*

* @author KangJian

*

*/

// MyBatis中Statement语句是通过RoutingStatementHandler对象的 prepare方法生成的，注解声明拦截此方法

@Intercepts({ @Signature(method = "prepare", type = StatementHandler.class, args = { Connection.class }) })

public class RebuildSqlInterceptor implements Interceptor {

static Logger logger = LoggerFactory.getLogger(RebuildSqlInterceptor.class);

public Object intercept(Invocation invocation) throws Throwable {

// long start = System.currentTimeMillis();

StatementHandler statementHandler = (StatementHandler) invocation.getTarget();

// 创建反射工具类，用于获取和设置SQL语句

MetaObject metaStatementHandler = SystemMetaObject.forObject(statementHandler);

// 获取拦截的SQL语句

MappedStatement mappedStatement = (MappedStatement) metaStatementHandler.getValue("delegate.mappedStatement");

BoundSql boundSql = (BoundSql) metaStatementHandler.getValue("delegate.boundSql");

// 获取本地线程变量

Long memberId = 0L;

try {

if (StringUtils.isNotEmpty(SaasParameter.getMemberId())) {

memberId = Long.parseLong(SaasParameter.getMemberId());

}

} catch (Exception e) {

logger.error("【noSaas拦截构建】会员ID转换异常，id=" + memberId, e);

}

if (!mappedStatement.getId().endsWith("noSaas")) {

// 当statement的id不以noSaas结尾，且memberId>0，则执行对INSERT与SELECT语句的重构

if ("SELECT".equals(mappedStatement.getSqlCommandType().toString()) && memberId > 0) {

List parameterMappings = boundSql.getParameterMappings();

metaStatementHandler.setValue("delegate.boundSql.sql", RebuildSqlUtils.rebuildQuery(boundSql.getSql(),

SaasParameter.getMemberId(), parameterMappings));

} else if ("INSERT".equals(mappedStatement.getSqlCommandType().toString()) && memberId > 0) {

metaStatementHandler.setValue("delegate.boundSql.sql",

RebuildSqlUtils.rebuildInsert(boundSql.getSql(), SaasParameter.getMemberId()));

}

} else {

// 当statement的id以noSaas结尾，为语句添加memberId额外参数

if ("SELECT".equals(mappedStatement.getSqlCommandType().toString())

|| "INSERT".equals(mappedStatement.getSqlCommandType().toString())) {

boundSql.setAdditionalParameter("memberId", memberId);

metaStatementHandler.setValue("delegate.boundSql", boundSql);

}

}

Object result = invocation.proceed();

// System.out.println("拦截耗时：" + (System.currentTimeMillis() - start));

return result;

}

public Object plugin(Object target) {

// 当目标类是StatementHandler类型时，才包装目标类，否者直接返回目标本身,减少目标被代理的次数

if (target instanceof StatementHandler) {

return Plugin.wrap(target, this);

} else {

return target;

}

}

public void setProperties(Properties properties) {

}

}